Red blood cell size and glycolytic enzyme activity: relationship to number of intramedullary cell divisions

In order to assess how the number of cell divisions influences the red blood cell (RBC) content of proteins other than hemoglobin, we measured the activity of two age-independent glycolytic enzymes in macrocytic, normal, and microcytic RBCs. The enzymes measured were phosphoglycerate kinase (PGK) and lactic dehydrogenase (LDH). In macrocytes, both PGK and LDH activity/10(10) RBCs were increased 1.6-fold over normal RBCs. In microcytes, however, the activity of these enzymes was identical to that seen in normal RBCs.